Full throttle only when the oil is warm?

Hello,

Since I can now see the oil temperature (in the reservoir) via AI for the first time in my Polo, I'm asking this question in the gasoline engine section.
A common piece of advice found on online forums is something like, "Don't push the engine to its maximum power output until the oil reaches at least 70°C," where 70°C is just an example.

Looking at the 2.0 TFSI engine, it appears to have essentially the same oil-water heat exchanger as the 1.9 TDI engines, specifically in the oil inlet line.
For me, this means that the oil from the reservoir isn't distributed to the lubrication points at its original temperature, but rather its temperature is brought closer to the water temperature beforehand – meaning it's either heated or cooled towards approximately 90°C as soon as the water reaches its operating temperature.
Okay, the VAG water temperature gauges are quite inaccurate during warm-up and often display 90°C when the actual water temperature is only around 70°C. But, if you continue for a few more minutes after reaching the 90°C mark, wouldn't it be okay to go full throttle, even if the oil in the reservoir, for example, is only 50°C?
What remains of the above-mentioned aspects in modern engines? Is the old-fashioned rule still in effect?

ulf wrote:

...even if the oil in the tub, for example, is only 50°C?

Do you really believe that it works like this:

- Water ~90°C
- Oil in the tub, temperature around 50°C.
- Oil is extracted from the reservoir and pumped through the heat exchanger.
- Does the oil reach all lubrication points with a minimum temperature of 70°C, or even more?

The contact time is far too short for so much to happen within this temperature range. Especially, warming up is always worse than cooling down, think about heat dissipation to the environment, etc.

TDI-GTI-4-Motion wrote:

The contact time is far too short for so much to happen within this temperature range.

For that reason, the oil is not only heated in the water cooler (WT), but also subsequently in the oil channels within the engine.

It is cold itself and loses a lot of heat through its surface.

What's the goal? Are you only driving short distances and need to push the engine hard? Why not trust the AI's oil temperature reading? In our VAG vehicles, it's usually quite accurate. Or did you disable them because of too much luxury?

Whatever, it shouldn't matter to me.

Ulf!

Please step aside! You're barking up the wrong tree again, and looking in the wrong place.

ulf wrote:

... What remains of the above-mentioned aspects in modern engines? Is there any

rule from the early Church left?

It still applies, but:
If you bring up an "old-fashioned rule," then quote it correctly and completely.

It's about a rule of thumb for when a motor is completely considered to be warmed up. And by "it," I mean the metal, not the oil!
In this process, the oil temperature of 90°C in the oil pan is used as a threshold. When the oil pan reaches this temperature, the engine is considered fully warmed up. Only then should the engine be fully loaded to minimize stress on the materials (in this case, the different metals). Because engines always have a certain amount of play, which decreases when the engine is warm, it is essential to wait for the warm-up phase to complete.

Therefore, this rule has absolutely nothing to do with the oil itself.

matthiasTDI96 wrote:

The (engine block) itself is cold and loses a lot of heat through its surface.

No, I'm talking about the situation where the "water temperature gauge shows 90°C, while the oil in the pan is around 50°C."

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Do you only drive short distances and need to really push the car?

It's not a necessity, but the acceleration is fun. It can be difficult to "cruise" or "stroll" until the engine oil has warmed up.

Bertil wrote:

It concerns a rule of thumb regarding when a motor is considered completely warmed up. And by "it," I mean the metal, not the oil! In this process, the oil temperature of 90°C in the oil pan is used as a threshold. When the oil pan reaches this temperature, the engine is considered to be fully warmed up. Only then should the engine be fully loaded to minimize stress on the materials (in this case, the different metals). Since engines always have a certain amount of "warm-up play," which decreases as the engine warms up, it is essential to wait for the warm-up phase.

Hmm... doesn't the circulated water (in the small circuit) distribute the heat within the engine block?
Okay, it needs to navigate through the metalwork and into the crankshaft and connecting rod bearings, relying on the flow of water and without any acceleration. If it takes approximately that long for the oil sump to reach 90°C, then the oil temperature is likely being used as an indicator for warming up the areas that are not cooled by water circulation. In that case, the logic behind the regulation becomes understandable.

Okay, so Bertil has already written about it. Also, the engine is still cold. Even water at 90 degrees Celsius needs a moment to warm up the engine. Furthermore, there are parts that don't have a water jacket. According to Bertil, and in my opinion, it makes sense to wait until all the internal components have reached operating temperature.

I have never used the water temperature gauge as an indicator. If anything, I use the oil temperature gauge. Or, depending on the ambient temperature in the morning, you can enjoy a leisurely ride of between 7 and 18 kilometers.

Right, what's the point of having oil that's 80°C warm if the piston hasn't yet reached a sufficient temperature for proper lubrication.

I would even go so far as to say that 50°C warm 5W-xx oil is perfectly adequate for a maximum of... The load from the motor would be sufficient, however, it wouldn't account for the component tolerances that are still present within the motor.

A complicating factor with newer engines that have active thermal management is that the coolant remains in the engine block for a relatively long time, while the cylinder head, due to the integrated exhaust manifold, is already at a much higher temperature.

Here, I really wonder how the different materials/metals are matched together. Back in the day, a blown head gasket would have been a major problem – I experienced it myself with my first car. It really breaks if you immediately floor the accelerator.

Okay, back to the topic: In the 3rd generation TFSI engine, the coolant in the cylinder head (and also as indicated on the instrument cluster) reaches 90 degrees Celsius, and only then does the engine block slowly start to warm up. Also, the oil temperature reaches 60 degrees Celsius relatively quickly. In the assumed example, oil heated to 60 degrees Celsius flows through the heat exchanger and then into the cold head.

Okay, and once everything is evenly heated, you can start guessing again and follow the rule of thumb of 15-20 kilometers.

Hi,

A significant portion of the heat generated in 4-stroke engines is absorbed in the cylinder head rather than in the engine block. Therefore, it is acceptable for the engine block to be cooled later. This could even lead to the ZK (zinc kernel) and block heating up more evenly, with fewer temperature differences.

Best regards, Rainer.

TDI-GTI-4-Motion wrote:

Right, what's the point of having oil that's 80°C warm if the piston hasn't yet reached a sufficient temperature for proper operation. I would even go so far as to say that 50°C warm 5W-xx oil is perfectly adequate for a maximum of... The load from the motor would be sufficient, but not the component tolerances that would then be present within the motor.

I would also see it that way .
Please watch this video starting at minute 14.
https://www.youtube.com/watch?v=Puq_lyp8C_o
Despite that, I make sure the engine is at least at its operating temperature and the oil is at 70 degrees Celsius before I put my foot down.

Hello again (it's been a while).

To gather more data on the topic, I conducted tests during a roughly 20-minute drive, including... I've extracted log data on water temperature and two different mold temperatures from the MSG, and I wanted to share it with you.
I'm not entirely sure how the two melting temperatures are measured or calculated in detail.
The Polo with the older EA113 engine has an oil pan sensor, but AFAIK it doesn't have any other oil temperature sensors. The log data labeled "Oil Temp Combined" shows -59°C for a short time after the engine starts, possibly while the oil level is being measured. Otherwise, they roughly correspond to the AI display, which only shows "---" when the temperature is below 50°C.
The dips in the log data represent short periods of minimal engine load, during which I didn't expect any significant oil temperature increase.
After the gas station stop, we got onto the highway, with a brief period of speeding.

It seems that the higher "oil temperature" reading, up to 83°C, is rigidly derived from the water temperature. Furthermore, the two melt temperatures seem to be somehow linked, as indicated by the small, parallel depressions shown in the red circle.
Does anyone have any ideas about what the MSG is doing with the higher "oil temperature" value?

I'm familiar with the issue of the calculated temperature from the temperature sensor on the air compressor in the Allroad.

If the temperature sensor on the compressor is defective or, for example, simply forgotten to be reattached, the compressor will overheat and be damaged.
The first temperature is the calculated value, which is always closer to the "threshold" than the actual temperature. This is to allow for intervention in case of a sensor malfunction.

ulf wrote:

... It seems that the higher "oil temperature" reading, up to 83°C, is rigidly derived from the water temperature. ...

What to expect, taking into account your engine's cooling system.

The oil temperature is being measured, and it should be reasonably accurate.
The oil temperature on the combination instrument is either calculated or measured by a separate temperature sensor. It should (if present) be located near the oil filter.


Your engine should have what's called a water-to-oil heat exchanger. This pre-warms the oil to approximately 80-90°C, and then the process reverses. After that, the oil is cooled by the water.
I am sorry, I cannot access external websites, including the one you provided. Therefore, I cannot translate the text from the given URL.

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Furthermore, the two melt temperatures seem to be somehow linked, as indicated by the small, parallel depressions shown in the red circle.

Therefore, I almost suspect that there is a second donor.
Alternatively, a fictitious temperature can be calculated based on the motor's load profile and (known) temperature model. I'm familiar with that from newer engines, but I can't confirm whether yours is one of them .

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Does anyone have an idea what the MSG is doing with the higher "oil temperature" value?

What do you mean by that?
At the very least, this method calculates the effective (i.e., actual) motor load.

Bertil wrote:

The oil temperature is measured and should be largely accurate.

Which of the two log values are you referring to? "Oil Temp" or "Oil Temp Combo"?

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The oil temperature on the combination instrument is either calculated or measured by a second temperature sensor. This

should be located near the oil filter or in its vicinity. In the wiring diagrams, I cannot find an oil temperature sensor other than the one located in the oil pan.

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Your engine should have what is called a water-oil heat exchanger. This heats the oil to approximately 80-90°C, and then the process reverses. After that, the oil is cooled by the water. http://www.kfz-tech.de/Biblio/Kuehlung/WaermetauscherOK.htm

Yes, the heat exchanger is installed.

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Therefore, I almost suspect that there is a second donor.

As I said, the SLP results do not show a second donor. Furthermore, it seems unlikely that two sensors at different locations would provide such strikingly synchronous readings of real values, considering factors like "slow creep heat" within the solid materials of the engine block, heat exchanger, etc.

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Alternatively, a fictitious temperature is calculated based on the load profile and the (known) temperature model of the motor. I'm familiar with that from newer engines, but I can't confirm whether yours is one of them

. That would be my guess.

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Quote: Does anyone have an idea what the MSG is doing with the higher "oil temperature" value? What do you mean by that?

What the MSG uses this value for.

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At the very least, this calculates the effective (i.e., actual) engine load.

What I understand as engine load (= the yellow line in the log image) is mainly calculated from air mass and engine speed. I know of several MED9.1 "tuner" setups with "modified" intake manifolds where the mass airflow sensor (MAF) provides significantly incorrect values - this is noticeable in the relationship between the actual values of air mass and boost pressure: in these cases, the engine load log data is also shifted accordingly based on the air mass, see, for example, https://turbolochblog.wordpress.com/2017/11/13/bosch-luftmassenmesser-hfm-6-vag-2-0-tfsi/.

ulf wrote:

Which of the two boolean values are you referring to? "OilTemp" or "OilTemp Combo"?

Oil temperature!

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As I said, the SLP images do not show a second donor.

Okay, that might be possible.

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Furthermore, it seems unlikely that two sensors at different locations would provide such strikingly synchronous readings of real values, considering factors like "slow creep heat" within the solid materials of the engine block, heat exchanger, etc.

Sure...
One is the temperature in the oil pan, and the other is the oil temperature at the oil filter or somewhere freely in the oil circuit.
The oil sump needs to react much more quickly to changes in load.

That's at least how it is with my Jetta. I have one sensor in the oil pan and one on the oil filter housing. With the sensor on the oil filter housing, you can practically feel every sudden change in engine load immediately through the temperature, while with the sensor in the oil pan, it takes a little longer for the load to be reflected in the oil temperature. In this case, only a longer change in load is noticeable in the oil sump.
In the Jetta, no computer alters the display of the oil temperature .

If you know the engine's temperature model, you can calculate one of the two oil temperatures based on the engine load.
"In your Polo, all input parameters are recorded by the computer using sensors. In my Jetta, I just pour fuel in using a 'watering can'. Air mass?" No matter what, just put in the fuel.

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... That would be my guess.

That's definitely possible. That's what people do these days.

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What the MSG uses this value for.

I'm sorry, I don't understand. Can you please rephrase your request?

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What I understand as "motor load" (= the yellow line in the log image) is mainly calculated from air mass and engine speed. I know of several MED9.1 "tuner" setups with "modified" intake manifolds where the mass airflow sensor (MAF) only provides significantly incorrect values - this is noticeable in the relationship between the logged values of air mass and boost pressure: in these cases, the motor load log data, based on the air mass, is also shifted accordingly, see, for example, https://turbolochblog.wordpress.com/2017/11/13/bosch-luftmassenmesser-hfm-6-vag-2-0-tfsi/

Ah... Now ...

While you can calculate the motor load from LM and n, you should definitely check it for plausibility. You can often tell a lot about it by checking the oil temperature.
You can also use it to calculate a load profile. That would be necessary, for example, for the LL service display (which I don't think your Polo has).
So, if someone starts the engine and immediately puts it under full load, that's a different stress profile compared to someone who gradually warms up the engine.
You cannot derive this statement from LM and n, but you can derive it (among other things) from the rate of change of the oil temperature.